With the development of data communication networks, network bandwidth is growing and there are more and more terminal devices. In order to reduce costs and converge the networks, the concept of data center has been proposed and supported by operators and equipment manufacturers, and it has good a prospect for development. As the equipment supporting the next generation data center Ethernet, the DCB (Data Center Bridging) needs to meet the requirements of the next generation data center network, including the support for significantly increasing terminal server devices.
To this end, IEEE802.1 DCB task group created two standard projects, namely IEEE 802.1 Qbh and IEEE802.1Qbg, to solve this problem. The Qbh standard defines Ethernet switch with extended ports to adapt to the ever-increasing demands for terminal device interfaces. The standard defines the Ethernet switch port extender module, and remote replication technology for multicast. The Qbg standard defines the edge virtual bridging (EVB) technology and standardizes the automatic discovery and configuration flow between end stations using the virtualization technology and switches connected with them. An end station supporting the EVB technology can comprise a group of virtual machines (VM), which are connected with an edge Ethernet switch through a virtual edge switch (VEB) or virtual edge port aggregator (VEPA). The VEPA technology requires that the switches support the Reflective Relay function, that is, forwarding the data out from the port at which the data is received.
FIG. 1 shows a schematic diagram of applying port extension to an Ethernet switch, and the part summarized in bold line is the Ethernet switch with extended port (Extended Bridge). The Extended Bridge comprises a bridge forwarding module such as the VLAN-aware Bridge Component and one or more Port Extenders, all of which constitute a controlling bridge, and there are at least one or more Port Extenders outside the Controlling Bridge. The Port Extenders inside the Controlling Bridge are called as internal Port Extenders, and the others are called as external Port Extenders. FIG. 1 shows a situation of one Controlling Bridge and two external Port Extenders. A group of instantiated ports connected between the VLAN-aware Bridge Component and the internal Port Extenders are called as a replication group. The End Station may be a single physical terminal or a device having a plurality of logical terminals that have realized virtualization.